Direct Torque Control of Pulse Width Modulation Current Source Inverter-fed Induction Motor by Novel Switching Method

This article proposes a new approach for direct torque control of induction motors. This method is based on direct torque control with pulse width modulation of a current source inverter using SIMULINK/MATLAB simulators for its performance assessment. The proposed control system is realized based on stator-flux-oriented reference. It uses the same method as direct torque control drive systems with a voltage source inverter to estimate the stator flux and electromagnetic torque and, therefore, only needs the stator resistance to control the motor. In this method, stator current components are calculated to directly control the stator flux and electromagnetic torque. Simulation results show the excellent performance of this system. Using simulations, the proposed method is also compared with the direct torque control voltage source inverter system, and it is shown that the proposed method improves induction motor performance and decreases the inverter switching losses. Another main advantage of the proposed control method is that it seriously limits the starting current and feeds the motor with high power quality. A novel switching method in space vector modulation of current source inverter is also proposed, which effectively decreases motor torque ripple and harmonic losses.